The present invention relates to a brush seal comprising a sealing element provided with a plurality of filaments or wires that are joined at a filament or wire end to form a filament or wire bundle and a clamp-like sealing housing for receiving and fixing the filament or wire end between a first and a second limb and for fixing the brush seal in a mounting recess of a housing. The invention also relates to a method for mounting a brush seal.
A great variety of brush seals of the type cited at the outset are known and are used—for example in gas turbines, to seal the intermediate space between a housing and a rotor, rotating at a relatively high speed, against leaks. A corresponding brush seal is described—for example in U.S. Patent Application Publication No. 2007/0132189 A1. The disadvantage of known brush seals, however, is that the basic rigidity of the brush seal required for the respective intended use must be adjusted with appropriate measures prior to mounting the brush seal in the respective machine. Thus, until now brush seals were built with a permanently-fixed free filament length. In this case, the free filament length is understood to be the section of the filament or wire bundle that is not surrounded by a clamping element, welding area, or adhesion area for fixing and bundling the individual filaments and wires. Thus, it was discovered, for example, when using Kevlar® brush seals in machine tool rotating unions, that the required leak tightness could only be achieved with very short filament lengths. In the process, it was observed that an unacceptably high heat build-up may occur. In order to limit this build-up of heat, the brush seal in this cited example is paired with the shaft in order to achieve the required basic stiffness of the brush seal. This approach is not economical and hard to control logistically. As a result, the objective of the present invention is making available a generic brush seal whose basic stiffness is adjustable.
A further objective of the present invention is providing a method for mounting a brush seal, which makes it possible to adjust and adapt the basic stiffness of the brush seal to the individual requirements of the environment being sealed.
A brush seal according to the invention has a sealing element provided with a plurality of filaments and wires, wherein the filaments and wires are joined at a filament or wire end to form a filament or wire bundle. In addition, the sealing element has a clamp-like sealing housing for receiving and fixing the filament or wire end between a first and a second limb and for fixing the brush seal in a mounting recess of a housing. The sealing housing is designed in such a manner that the first limb is configured to be shorter than the second limb, wherein the second limb rests, by means of its outer contour, against an inner side of the mounting recess, and at least one partial area of the inner contour of the second limb is adjacent, in the region of an outlet opening for a free area of the filament or wire bundle that protrudes from the housing and that is opposite from the filament or wire end, to the free end, and is adjacent to an area of the free end of the filament or wire bundle that is opposite from the partial area at least partially at the outlet opening. In addition, the first limb rests against an inner side of the mounting recess. In the case of the brush seal according to the invention, the basic stiffness of the filament or wire bundle or the seal is not adjusted until after mounting or until the time the brush seal is mounted in the housing. In the process, the filaments or wires are clamped between the second limb of the sealing housing and the outlet opening of the mounting recess. The length of the second limb of the sealing housing may be varied so that the free filament length and thus the basic stiffness of the brush seal may be adapted individually to the requirements of the environment being sealed. In addition, the brush seal may be fabricated with normal fabrication tolerances, because any applicable very high basic stiffness of the brush seal is achieved after mounting the brush seal. As a result, the leak tightness as well as the heat build-up may be adjusted, for example, during operation without the brush seal having to be paired with a shaft. The costs of manufacturing and mounting as well as logistical time and effort are thereby reduced considerably. Thus, the brush seal can be fabricated with long filaments that have a low basic stiffness. When the brush seal is mounted, the filaments or wires are clamped in a predetermined area by the sealing housing and the outlet opening of the mounting recess in such a way that the clamped filaments or wires function in a manner analogous to a brush seal having shorter filaments.
In an advantageous embodiment of the brush seal according to the invention, the filament or wire end is fabricated of a core wire, around which the plurality of filaments or wires is wound and a clamping element, in particular a clamping tube, wherein the clamping element is used for fixing and bundling the filaments and wires. However, it is also possible for the filament or wire end to have a welding or adhesion area for fixing and bundling the filaments and wires. According to the invention, different types of sealing elements may be used.
In other advantageous embodiments of the brush seal according to the invention, the sealing housing is configured to be one-piece or the first and second limbs of the sealing housing are configured as separate structural elements. In this case, the sealing housing may be made of metal, a meal alloy, plastic or ceramic. The sealing housing may be adapted advantageously to the respective requirements of the areas of the machine being sealed.
In other advantageous embodiments of the brush seal according to the invention, the second limb of the sealing housing is configured in such a manner that it projects out of the outlet opening of the mounting recess. As a result, very high levels of basic stiffness of the brush seal may be achieved advantageously. In addition, the partial area with which the second limb is adjacent to the filament or wire bundle of the brush seal may be configured to be spaced apart from the free end of the filament or wire bundle. This makes it possible to advantageously avoid undesired contact between the sealing housing and/or the second limb and opposing machine parts.
According to other advantageous embodiments of the brush seal according to the invention, the housing in which the brush seal is mounted may be a structural element of an aircraft or stationary gas turbine, a compressor, a steam turbine or a machine tool. Basically, the brush seal may be used in all machines in which a gap between two structural elements of the machine must be sealed.
A method for mounting a brush seal in a housing according to the invention includes the following steps: a) Making available a brush seal comprising a sealing element provided with a plurality of filaments or wires that are joined at a filament or wire end to form a filament or wire bundle and a clamp-like sealing housing for receiving and fixing the filament or wire end between a first and a second limb, wherein the sealing housing is designed in such a manner that the first limb is configured to be shorter than second limb and b) Inserting and fixing the brush seal in a mounting recess of the housing, wherein the second limb rests, by means of its outer contour, against an inner side of the mounting recess, and at least one partial area of the inner contour of the second limb is adjacent, in the region of an outlet opening for a free end of the filament or wire bundle that protrudes from the housing and that is opposite from the filament or wire end, to the free end, and is adjacent to an area of the free end of the filament or wire bundle that is opposite from the partial area at least partially at the outlet opening, and the first limb rests against an inner side of the mounting recess. In the case of the method according to the invention, the basic stiffness of the filament or wire bundle or the seal is not adjusted until after mounting or until the time the brush seal is mounted in the housing. In the process, the filaments or wires are clamped between the second limb of the sealing housing and the outlet opening of the mounting recess. The length of the second limb of the sealing housing may be varied so that the free filament length and thus the basic stiffness of the brush seal may be adapted individually to the requirements of the environment being sealed.
Other advantages, features and details of the invention are disclosed in the subsequent description of an exemplary embodiment that is depicted graphically.